Fiber bragg grating wavelength demodulator

Abstract

The invention discloses a fiber bragg grating wavelength demodulator which comprises a broadband flat light source, a circulator, a fiber bragg grating, a beam splitter, a plurality of narrow-band transmission optical filters, a photodiode, a trans-impedance amplifier and a differential amplification circuit. The inclination angles of two adjacent narrow-band transmission optical filters are different, and the narrow-band transmission optical filters and the corresponding amplification and differential circuits form wavelength demodulation channels. The narrow-band transmission optical filters with different preset angles are utilized to realize that the change relation of transmission light intensity along with the increase of wavelength is just opposite, a photodiode is utilized to convert an optical signal into a current signal, and a trans-impedance amplifier is utilized to convert the current signal into a voltage signal and amplify the voltage signal; and the two voltage signals are differentiated and amplified by a differential amplifier to obtain the relationship between the differential signal and the central wavelength of the FBG. Compared with other FBG wavelength demodulation devices, the wavelength demodulation device has the advantages that the structure is simple, the demodulation speed is high, the demodulation speed is about 100 MHz, and the demodulation precision is about + / -5 pm.

Description

technical field [0001] The invention belongs to the wavelength demodulation technology of fiber grating, in particular to a fiber grating wavelength demodulator. Background technique [0002] The center wavelength of fiber grating FBG is directly related to parameters such as stress, temperature, oscillation, etc. It has anti-corrosion, anti-electromagnetic interference, good long-term stability, small size, light weight, reusability, fatigue resistance, and can be embedded in composite material structure Moderate advantages, widely used in wind turbine blade strain measurement, mine tunnel monitoring, aircraft engine temperature measurement, oil well detection and so on. Through the fiber grating FBG wavelength demodulation, parameters related to parameters such as stress, temperature, and oscillation can be measured, and it has the characteristics of high sensitivity and high precision. [0003] The traditional method of measuring the wavelength change is to directly use ...

AI Technical Summary

Problems solved by technology

[0009] Tunable filter method: The hysteresis effect of the piezoelectric ceramics of the tunable filter is obvious, the wavelength of the outgoing light is unstable, and the adaptability to harsh environments is not strong;

[0010] Scanning DFB laser method: It is greatly affected by temperature changes, the measurement range is small, and the speed is slow. It is only suitable for small-capacity fiber grating demodulation systems;

[0011] Infrared CCD spectrum demodulation method: complex process, high cost, difficult to expand channels

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